聚乳酸-聚吡咯/银多层复合抗菌薄膜的制备与性能表征

目的提高聚乳酸(PLA)薄膜的抗菌性能。方法受到导电高分子材料可以通过静电作用方式起到抗菌作用的启发,利用Fe~(3+)引发吡咯(Py)在PLA薄膜表面发生化学氧化反应,聚合形成抗菌涂层(PPy),成功制备出PLA-PPy多层复合抗菌薄膜。采用等物质的量Ag~+替代Fe~(3+),引发Py在PLA薄膜表面聚合形成双重抗菌涂层(PPy/Ag),成功制备出PLA-PPy/Ag多层复合抗菌薄膜,并探讨了不同氧化剂和Py浓度对多层复合薄膜结构和性能的影响。结果当PLA薄膜表面积为72 cm~2,水溶液体积为40 mL,Fe Cl_3·6H_2O的浓度为0.047 mol/L,Py的浓度为0.223 mol/L时,PLA-PPy多层复合薄膜的表面PPy层结构致密,拉伸强度(40.1 MPa)和断裂伸长率(24.9%)分别降低了7.6%和12.6%,热稳定性得到较为明显的提高。此外,PLA-PPy/Ag与PLA-PPy多层复合薄膜表现出相似的力学性能和热稳定性。更为重要的是,相比于PLA-PPy多层复合薄膜,PLA-PPy/Ag多层复合薄膜表现出更为优异的抗菌特性,大肠杆菌的菌落总数降低至2.9×10~6 CFU/cm~2,相比于纯PLA薄膜(4.8×10~(10) CFU/cm~2),降低了超过4个数量级。结论相比于完全采用成本较高的纳米银离子负载抗菌方式来说,较低成本的双重抗菌涂层(PPy/Ag)将会在PLA活性包装领域具有一定的研究意义。

Preparation and Characterization of Polylactic Acid-Polypyrrole/Silver Multilayer Composite Antibacterial Film

The work aims to improve antibacterial properties of polylactic acid (PLA) film. Inspired by the fact that conductive polymer materials could exert antibacterial effect through electrostatic interaction, Fe3+ was applied to induce the chemical oxidation polymerization of pyrrole (Py) on the surface of PLA film to form antibacterial coating (PPy), so as to prepare PLA-PPy multilayer composite antibacterial film. Moreover, double antibacterial coating (PPy/Ag) was formed on the surface of PLA film by using the equivalent amount of Ag+ instead of Fe3+ to induce the polymerization of Py, and PLA-PPy/Ag multilayer composite antibacterial film was also successfully prepared. The effects of different oxidants and Py concentrations on the structure and properties of multilayer composite films were further investigated. When PLA film surface area, aqueous solution volume, FeCl3?6H2O concentration, and Py concentration were 72 cm2, 40 mL, 0.047 mol/L and 0.223 mol/L respectively, PPy layer of PLA-PPy multilayer composite antibacterial film was compact, but tensile strength (40.1 MPa) and elongation at break (24.9%) of PLA-PPy multilayer composite film were only reduced by 7.6% and 12.6% respectively and thermal stability of PLA-PPy multilayer composite film was significantly improved. Moreover, PLA-PPy/Ag and PLA-PPy multilayer composite film showed similar mechanical properties and thermal stability. More importantly, compared with PLA-PPy multilayer composite film, PLA-PPy/Ag multilayer composite film showed better antibacterial properties, and the total number of Escherichia coli colonies decreased to 2.9×106 CFU/cm2, which was more than 4 orders of magnitude lower than that of the pure PLA film (4.8×1010 CFU/cm2). Compared with the nano silver antibacterial method with high cost, double antibacterial coating (PPy/Ag) with lower cost will have certain research significance in the field of PLA active packaging.